..... if they fit him, but it largely depends upon which girl the shorts actually belong to.
He can also wear her skirt on appropriate occasions, but only if she gives him her permission / approval.
Sure, if they fit. Just expect to be ridiculed as it is not greatly accepted by society.
No and you're a f#g if you do, be a real man, and wear your own cloths!
No. Final answer.
If he wants to.